ABSTRACT
The current research aims to investigate the residual compressive strength of normal, high and ultra-high strength concrete containing local electric arc furnace steel slag (eafss) as a replacement of the used natural aggregate after exposure to elevated temperatures. Specimens of thirty concrete mixes with different intended compressive strengths were prepared and after 28 days the compressive strength was obtained at the ambient and elevated temperatures. The research investigates the effect of elevated temperature degree (250 c and 550 c) for an exposure period equals 120 minutes on the concrete compressive strength. The studied mixes reflect the key variables considered in the current study which are; the replacement percentage of the natural coarse aggregate by the used eafss, the cement content, the silica fume percentage and the presence of eafss fine aggregate. The results showed that using eafss as a coarse aggregate in concrete mixes increased the residual compressive strength after exposure to elevated temperatures. In general, the reduction in the compressive strength due to the exposure to elevated temperatures decreased as the replacement percentage of eafss coarse aggregate increased.
Also, it was shown that the occurred reductions in the concrete compressive strength was increased in mixtures of high and ultra- high strength concrete than those of normal strength concrete. In addition, it was shown that specimens of mixes of higher contents of cement and silica fume exploded after exposure to 550 c.